Holographic image generated based on eye position

ABSTRACT

A holographic display system includes an eye tracker configured to determine a position of a feature of an eye, a light source configured to output image light, and a digital dynamic hologram. The digital dynamic hologram is configured to receive the image light from the light source. The digital dynamic hologram is further configured to spatially modulate the image light based on a target image to form a reconstructed image in the eye. The reconstructed image includes noise that is non-uniformly distributed across the reconstructed image based on the position of the feature of the eye.

BACKGROUND

Holographic displays can form two-dimensional (2D) and three-dimensional(3D) distributions of light that emulate a real-life visual experience.Holographic displays can be used to provide augmented reality (AR)experiences and/or virtual reality (VR) experiences by presentingvirtual imagery directly to a user's eye. Such virtual imagery can takethe form of one or more virtual objects that are displayed such thatthey appear as if they are physical objects in the real world.

SUMMARY

A holographic display system includes an eye tracker configured todetermine a position of a feature of an eye, a light source configuredto output image light, and a digital dynamic hologram. The digitaldynamic hologram is configured to receive the image light from the lightsource. The digital dynamic hologram is further configured to spatiallymodulate the image light based on a target image to form a reconstructedimage in the eye. The reconstructed image includes noise that isnon-uniformly distributed across the reconstructed image based on theposition of the feature of the eye.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Furthermore,the claimed subject matter is not limited to implementations that solveany or all disadvantages noted in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows an example near-eye display device.

FIG. 2 schematically shows an example holographic display system thatmay be implemented in a near-eye display device.

FIG. 3 shows an example target image.

FIGS. 4-6 show example reconstructed images of the target image of FIG.3 that are generated based on different positions of features of an eye.

FIG. 7 schematically shows an example iterative hologram designalgorithm.

FIG. 8 shows a graph depicting aspects of the iterative hologram designalgorithm of FIG. 7.

FIG. 9 is a flow chart depicting aspects of an example holographicdisplay method.

FIG. 10 schematically shows an example computing system.

DETAILED DESCRIPTION

Computer-generated holograms (CGHs) can be used to form an image in auser's eye. A computer-generated hologram may be complex—i.e., thehologram may include both amplitude and phase components. Typically, acomputer-generated hologram may modulate only one of the complexcomponents to reconstruct an image. For example, a computer-generatedhologram may modulate the phase of a wavefront of incident light, whilethe amplitude as a function of the phase remains constant and as closeto unity as possible. However, there is no exact solution where theamplitude fully converges to unity when the phase is modulated. Thisdeviation from unity causes noise to be introduced into an imagereconstructed by the computer-generated hologram.

Accordingly, the present disclosure is directed to a holographic displayapproach that leverages the visual and physiological characteristics ofthe eye to obscure noise in an image from being perceived by a user. Inparticular, a position of a feature of a user's eye may be determined.For example, the feature may include a fovea in a retina of the user'seye. Furthermore, a computer-generated hologram may be designed suchthat noise may be non-uniformly distributed across an image based on thedetermined position of the feature of the eye. Referring to the aboveexample, noise may be positioned in regions of the image that areperipheral to the determined position of the fovea, where the perceptivepower of the eye is weaker. In accordance with this holographic displayapproach, the image may be perceived by the user as being of higherquality, since the noise is less perceptible by the user. Moreover, suchimage quality improvement may be realized without introducing anyadditional components to a holographic display system. In anotherexample, noise is positioned based on a determined position of theuser's pupil, so that the noise is not perceptible to the user.

FIG. 1 shows an example holographic display device in the form of anear-eye display device 100. The display device 100 includes right-eyeand left-eye holographic display systems 102R and 102L mounted to aframe 104 configured to rest on a wearer's head. Each of the right-eyeand left-eye holographic display systems 102 include light-manipulatingimage display componentry configured to project computerized virtualimagery into left and right eyes of a wearer of the display device 100.In one example, the light-manipulating image display componentryincludes one or more holographic optical elements. An exampleholographic display system representative of the right-eye and left-eyeholographic display systems 102R and 102L is described in more detailbelow with reference to FIG. 2.

In some implementations, the right-eye and left-eye holographic displaysystems 102R and 102L include a field of view (FOV) that is wholly orpartially transparent from the perspective of the wearer, to give thewearer a view of a surrounding real-world environment. In otherimplementations, the FOVs of the right-eye and left-eye display systems102R, 102L are opaque, such that the wearer is completely absorbed invirtual-reality (VR) imagery provided via the near-eye display device.In yet other implementations, the opacities of the FOVs of the right-eyeand left-eye holographic display systems 102R, 102L may be dynamicallycontrolled via a dimming filter. A substantially see-through displaywindow, accordingly, may be switched to full opacity for a fullyimmersive virtual-reality experience.

Display device 100 includes an on-board computing system in the form ofa controller 106 configured to render the computerized display imageryvia the right-eye and left-eye holographic display systems 102R, 102L.The controller 106 is configured to send appropriate control signals tothe right-eye holographic display system 102R to form a right-eye image.Likewise, the controller 106 is configured to send appropriate controlsignals to left-eye holographic display system 102L to form a left-eyeimage. The controller 106 may include a logic subsystem and a storagesubsystem, as discussed in more detail below with respect to FIG. 10.Operation of the display device 100 additionally or alternatively may becontrolled by one or more remote computing device(s) 108 (e.g., incommunication with a display device 100 via a local area network and/orwide area network).

FIG. 2 schematically shows an example holographic display system 200 insimplified form. For example, the holographic display system 200 may beincorporated into a display device, such as near-eye display device 100of FIG. 1. In particular, the holographic display system 200 may berepresentative of the right-eye or left-eye holographic display systems102R, 102L of the display device 100 of FIG. 1. In another example, theholographic display system 200 may be incorporated into a computingsystem 1000 of FIG. 10. Generally, the holographic display system 200may be incorporated into any suitable display device configured todirect coherent illumination light through a digital dynamic hologram toform an image. In some implementations, the holographic display systemmay be incorporated into a large-format display device, a projectiondisplay device, a mobile display device (e.g., smartphone, tablet), oranother type of display device.

Holographic display system 200 is operable to position an exit pupil andprovide an eyebox in which virtual imagery generated by the holographicdisplay system is viewable by a user's eye. As used herein, an “eyebox”refers to a two-dimensional plane in which a human eye pupil can receiveimage light from the holographic display system 200. In practicalimplementations, the eyebox need not be a plane or rectangle, though itwill be described herein as such for the sake of simplicity. It will beunderstood that FIG. 2 depicts aspects of the example holographicdisplay system 200 schematically, and is not drawn to scale.

Holographic display system 200 includes a light source 202 configured tooutput light 204 at any of a range of angles. In some examples, thelight source 202 may include a directional backlight. In some examples,the light source 202 may include a micro-projector and a steerablemicromirror. In other examples, different light sources arranged atdifferent angles may be used to vary an input angle by selecting whichlight to use for illumination, or any other suitable method of varying alight input angle may be used. The light source 202 may be configured tooutput collimated light 204, that may be spatially modulated by adigital dynamic hologram (DDH) 206 to create an image. Additionally oralternatively, the light source 202 may include any suitable optics foroutputting light for creating and projecting images. In someimplementations, the light source 202 may include a spatial lightmodulator for creating an image. The term “light source” is used hereinas any suitable optics for outputting light to the other depictedcomponents, whether the light does or does not encode an image.

The light 204 output from light source 202 may be substantiallymonochromatic or multi-color (e.g., red, green, blue). In some examplesthat utilize multi-color light, light source 202 may perform colorfield-sequential display. For implementations in which aberrationcorrection components are used to correct for any aberrations in theexit pupil (e.g., caused by steering of the exit pupil), such componentsmay be independently controlled for each color channel to provideaberration correction suited for each color channel. One example of suchcorrective components may include a phase modulating display panel, suchas a transmissive liquid crystal panel or a reflective liquid crystal onsilicon (LCOS) display. Other corrective elements may include a liquidcrystal (LC) lens, a micromirror array, and a deformable mirror, asexamples.

In the depicted example, light 204 output from light source 202 isintroduced into the DDH 206. Although the light rays exiting the lightsource 202 and entering the DDH 206 are depicted as being parallel toeach other, in practice the light rays may be converging or diverginglight rays. While not depicted in FIG. 2, one or more in-couplingelements optionally may be provided to facilitate in-coupling of light204 into the DDH 206.

The DDH 206 may be configured to form at least a portion of virtualimagery that is projected toward a user's eye 208. For example, the DDH206 may be logically partitioned into a plurality of digital hologramsthat each form part of an image using light 204 from the light source202. The plurality of digital holograms may be formed by partitioning asingle image producing panel and/or by providing multiple separate imageproducing panels. The DDH 206 may be configured to produce imagery viafirst order diffracted light, and/or through the use of other orders ofdiffracted light. In some implementations, the DDH 206 may be areflective element. In other implementations, the DDH 206 may be atransmissive element.

By using a DDH 206 for image formation, there is no need for additionalrelay optics between the DDH 206 and the user's eye 208. This allows fora compact and scalable near-eye display device. In addition, the DDH 206may be relatively large in size, which helps to decrease aperturediffraction, and thus improve image quality relative to a micro-display.Moreover, such a configuration may be optically efficient relative toother configurations that use a micro-display, as light is primarilysteered rather than attenuated to form the image. Further, aberrationsin any optical components may be corrected by the DDH 206. Additionally,the pixels in the DDH 206 can be as small as desired, as diffractiveeffects are used to form the image. In other words, there is no minimumpixel size requirement in order to achieve a desired resolution.

The DDH 206 may be configured to receive light 204 from the light source202. The DDH 206 may be configured to split the light 204 into myriaddifferent light rays corresponding to image pixels. In the depictedexample, only two pixels of the image are shown as solid and dottedparallel light rays. Note that the parallel light rays correspond topoints of infinity, but it is also possible to have diverging light raysindicating points at a certain distance for the user's eye 208.

The DDH 206 may be configured to modulate the phase of the incidentwavefront of the light 204 at each pixel. In particular, the DDH 206 maybe configured to spatially modulate image light 210 to enter the user'seye 208 via human eye pupil 212 and strike the retina 214, causing thelight 210 to be perceived as the reconstructed image. Although FIG. 2depicts the parallel light rays stopping at a point outside of the humaneye pupil 212, this is for illustration purposes only. In practical use,the image light 210 may converge toward a focal point that lies before,within, or beyond the human eye 208. In some examples, the exit pupilformed by the DDH 206 may coincide with the human eye pupil 212. Lightentering the human eye pupil 212 may be focused by the eye lens tomodify the light's focal point, for example to focus the light at theretina 214. When light is stereoscopically projected toward retinas ofboth eyes at once, the virtual imagery may be perceived as athree-dimensional object that appears to exist at a three-dimensionalposition within the user's environment, some distance away from theuser.

The DDH 206 may be configured to spatially modulate the light 204 basedon a target image to form a reconstructed image in the user's eye 208.The target image may be generated by a controller 220 that isoperatively connected to the light source 202 and the DDH 206. FIG. 3shows an example of a target image 300 that may be generated by thecontroller 220 of FIG. 2. Note that the target image 300 as depicted isfree from any random noise. The controller 220 may generate the targetimage 300 in any suitable manner. The goal of holographic display systemis to cause the reconstructed image to replicate the target image withnoise that is minimally perceptible to the user.

The target image 300 may include a plurality of image pixels. Each imagepixel may have a target intensity. Further, the DDH 206 may beconfigured, for each of a plurality of display pixels corresponding tothe plurality of image pixels of the target image, to modulate a phaseof an incident wavefront of the image light 204 based on the targetintensity of the corresponding image pixel to output an actualintensity. The difference between the target intensity and the actualintensity may be based on a noise threshold that is determined based ona position of the display pixel within the reconstructed image relativeto a determined position of a feature of the user's eye as discussed infurther detail below.

As discussed above, the reconstructed image projected from the DDH 206into the user's eye 208 may include noise that is non-uniformlydistributed across the reconstructed image based on a position of afeature of the user's eye 208. In particular, the image noise may bepositioned away from the position of the determined feature in order toobscure the noise such that it is less perceptible by the user's eye208. To facilitate such functionality, the holographic display system200 includes an eye tracker 218 configured to track a current positionof a feature of the user's eye 208. In some examples, the eye tracker218 may be configured to track the position of the pupil 212. Forexample, the eye tracker 218 may include a light source that projectslight onto the use's eye 208, and the eye tracker 218 may include animage sensor that captures light reflected from a cornea of the user'seye with which glints and/or other features can be identified todetermine the pupil position. In some examples, the eye tracker 218 maybe configured to determine a diameter and/or perimeter of the pupil 212.

The eye tracker 218 may be configured to track the position of the fovea216 in the retina 214 of the user's eye 208. In some examples, the eyetracker 218 may be configured to determine the position of the fovea 216via direct measurement. In some examples, the eye tracker 218 may beconfigured to derive the position of the fovea 216 from the measuredposition of the pupil 212 or based on measuring another aspect of theuser's eye 208.

It will be appreciated that the eye tracker 218 may be configured todetermine the position of any suitable feature of the user's eye 208.Further, the eye tracker 218 may employ any suitable eye trackingtechnology to track the position of a feature of the user's eye.

The eye tracker 218 may be configured to provide the tracked position ofthe feature of the user's eye 208 to the controller 220, which may beconfigured to control the light source 202 and the DDH 206 inconjunction to form the reconstructed image in the user's eye 208.

The controller 220 may be implemented as any suitable processingcomponentry, including a logic subsystem and storage subsystem asdescribed below with respect to FIG. 10. It will be understood that thecomponents and arrangements shown in FIG. 2 are presented for the sakeof example and are not limiting.

The reconstructed image includes noise that is non-uniformly distributedacross the reconstructed image based on the position of the trackedfeature of the user's eye 208. In some implementations, the pupil 212 ofthe user's eye 208 may be used as a mask for the noise. In suchimplementations, the holographic display system 200 may be configured toform an eyebox that is larger than a maximum pupil diameter of theuser's eye 208. FIG. 4 shows an example reconstructed image 400generated based on the target image 300 shown in FIG. 3. Thereconstructed image 400 includes a central region 402 that falls withina perimeter 404 of the pupil of the user's eye and a peripheral region406 that falls outside of the perimeter 404 of the pupil of the user'seye. The peripheral region 406 can be treated as a “do not care area”when designing the hologram, as any light incident on this area will beblocked from being received by the retina, and thus not perceived by theuser's eye. The holographic display system 200 may be configured todistribute more noise in the peripheral region 406 and less noise in thecentral region 402 of the reconstructed image 400. In some examples, thecentral region 402 of the reconstructed image 400 may includesubstantially little or no noise.

For this example, a circular binary mask may be is used within ahologram design algorithm (HDA) for generating the reconstructed imagein order to mimic the physical shape of the eye pupil. In a practicalapplication of this approach, the eye tracker 218 may accurately trackthe position of the pupil 212 of the user's eye 208 and the holographicdisplay system 200 may dynamically adjust the size and/or position ofthe central region 402 and the peripheral region 406 of thereconstructed image 400 based on the determined position and size of thepupil 212 to allow the image to be formed in the correct location toobscure the undesired noise from being perceived by the user.

In some implementations, a reconstructed image may be generated based ona position of the fovea 216 in the retina 214 of the user's eye 208 asdetermined by the eye tracker 218. In such implementations, theholographic display system 200 may be configured to distribute noisewithin the reconstructed image in a manner that mimics the perceptivefield of the human eye. In other words, the noise may be positioned inthe peripheral region (outside the fovea) where the perceptive power ofthe eye is reduced. FIGS. 5 and 6 show example reconstructed images 500and 600 generated based on the target image 300 shown in FIG. 3. In FIG.5, a reconstructed image 500 includes a plurality of different regions(e.g., 504, 506, 508, 510) that are dynamically determined based on theposition 502 of the fovea 216 of the user's eye 208. For example, theuser may be looking at the moon in the upper left corner of the image.In the depicted example, the plurality of different regions of thereconstructed image 500 are concentric regions centered on the position502 of the fovea 216 of the user's eye 208. For example, the concentricregions may be formed using a rotationally symmetric function. Eachregion may have a different noise threshold. The central foveal region504 is given preference in terms of optimization for noise reduction,resulting in near-perfect image formation in this region. Outside of thefoveal region, a graduated drop-off in quality is achieved using agraduated mask to maximize perceived visual quality. In other words, theregions that are closer to the position 502 of the fovea 216 of theuser's eye 208 may include less noise and the regions further from theposition of the fovea 216 of the user's eye 208 may include more noise.In this way, noise may be distributed around the edges of thereconstructed image 500, that is in the periphery of the user's vision.

The eye tracker 218 is used to determine at what location the user iscurrently looking (e.g., the position of the fovea), and the holographicdisplay system 200 is configured to dynamically center the plurality ofregions of the reconstructed image on this location. As the user's eyemoves, the regions of the reconstructed image with the lowest noise(i.e., highest quality) tracks the position of the fovea 216 of theuser's eye 208.

FIG. 6 shows a reconstructed image 600 generated based on an updatedposition of the fovea 216. For example, the user may be looking at thebase of the mountains in the lower right corner of the image. Thereconstructed image 600 includes a plurality of different regions (e.g.,604, 606, 608, 610) that are dynamically determined based on theposition 602 of the fovea 216 of the user's eye 208. The central fovealregion 604 is given preference in terms of optimization for noisereduction, resulting in near-perfect image formation in this region.Outside of the foveal region, a graduated drop-off in quality isachieved with regions that are closer to the position 502 of the fovea216 having less noise and the regions further from the position of thefovea having more noise. This has the effect of providing near-perfectimage quality across the whole field of view. Noise in the edges of theimage is not perceived due to the lower resolution of the eye in theperiphery.

The concentric regions of the reconstructed images are provided as anexample and are meant to be non-limiting. It will be appreciated thatthe holographic display system 200 may divide a reconstructed image intoany suitable number of different regions having different noisethresholds. In some examples, a region may be as small as a singlepixel. In some implementations, a reconstructed image may be dividedinto a foveal region and a peripheral region. In some suchimplementations, the foveal region may have little or no noise, andnoise outside of the foveal region may be smoothly graduated from theperimeter of the foveal region to the periphery of the reconstructedimage. In some implementations, noise may be distributed in areconstructed image as a function of a pixel's relative distance to aposition of the fovea (or another feature of the user's eye). It will beappreciated that the holographic display system may non-uniformlydistribute noise within a reconstructed image in any suitable manner.

The controller 220 of the holographic display system 200 may employ aholographic design algorithm (HDA) to generate a reconstructed imageaccording to the approach described herein. FIG. 7 schematically showsan example HDA 700 that may be employed by the holographic displaysystem 200. The HDA 700 involves an iterative cycle of forward andbackward Fourier transforms with amplitude constraints imposed at eachiteration. The HDA 700 imposes amplitude conditions on the hologramplane, h(x, y) and image plane g(u, v) while allowing their phases todrift into an optimum value. The coordinates of the hologram plane are xand y and of the image plane u and v. For simplicity x, y, u and v areomitted and the hologram plane is denoted as h and the image plane isdenoted as g.

For iteration n of the HDA 700, at 702, the image plane g_(n) isassigned the intensity of the target image G₀ and a designated phase(e.g., a random phase). At 704, the hologram plane, h_(n) is computedusing the inverse Fourier transform of the image plane. The hologramplane is now a complex function with variable amplitude. Since thephase-only hologram, h_(n) is used, amplitude of unity is imposed on thehologram plane at 706. In the next step, at 708, the Fourier transformof the phase-only hologram is computed and the image plane g′_(n) isfound. The amplitude of the nth image plane g_(n) is used to calculatethe error between the actual reconstruction g′ and the target image G₀.The error is used to change the amplitude of the target image plane intoG_(n), which is the next target image. In general, if a point on theimage plane has value smaller that the target value, the value of G_(n)will change such that it encourages an increase of its value. At 710, afeedback function is applied using a threshold M that may change basedon a position of the pixel relative to the position of the fovea (oranother feature of the eye). This is described mathematically as:

G_(n)=Mask(Target_Image−Error*Feedback_Parameter)+(1−Mask)*Current_Image

or

G _(n) =M[G ₀+(G ₀ −|g′ _(n)|)k]+(1−M)|g′_(n)|

When Mask=0 the image pixels for the next iteration are left unchanged,i.e. to the same value in the next iteration as the current. Thisminimizes the constraints imposed on the hologram design for that regionand leaves more freedom for the rest of the image (to reduce noise).When M==1, pixels are pushed to get their target value defined by theTarget_Image combined with the error and the Feedback_Parameter. Thevalue of M may change according to different regions that mimic theperceptive field of the eye. The value of M may be greater closer to thefoveal region to allow for less (or no noise). Further, the thresholdmay drop outside this region with the remainder of the image having alower threshold that allows for more noise.

FIG. 8 shows an example of different regions of a reconstructed imagehaving different threshold values for a n^(th) iteration of the HDA 700.In this example, the target intensity of G₀=100. The reconstructed imageintensity g′_(n)=90. If the pixel is placed in the foveal region (region1), the threshold value for G_(n) for that pixel is set to 105 in orderto ensure that the reconstructed intensity is pushed up to the targetintensity in the next iteration so that minimal noise is produced. Ifthe pixel is placed in the adjacent region (region 2), the thresholdvalue is set to 100 so that it is likely that the reconstructedintensity reaches the target intensity. The other peripheral regions(region 3 and region 4) have lower threshold values (97, 93) that createadditional freedom, which is manifest as higher variance noise. Thelower thresholds in the peripheral regions allow for greateroptimization of the foveal region (region 1) and hence lower variancenoise. As such, higher quality can be achieved in the foveal region thancould be achieved relative to distributing noise uniformly across theimage.

The HDA 700 may repeated the iterative process repeated until thephase-only hologram converges into a value that forms the target imagewith acceptable quality based on the particular noise threshold.

The HDA 700 is provided as an example and is meant to be non-limiting.Other HDAs may be contemplated. In some examples, a non-iterative HDAmay be employed by the holographic display system 200.

FIG. 9 depicts aspects of an example holographic display method 900. Forexample, the method 900 may be performed by the holographic displaysystem 200 shown in FIG. 2. Generally, the method 900 may be performedby any suitable holographic display device. At 902, the method 900includes determining, via an eye tracker, a position of a feature of aneye. In some implementations, the feature may include an eye pupil. Insome implementations, the feature may include a fovea in a retina of aneye. At 904, the method 900 includes generating a target image. At 906,the method 900 includes directing image light from a light source to adigital dynamic hologram. At 908, the method 900 includes spatiallymodulating, via the digital dynamic hologram, the image light based onthe target image to form a reconstructed image in the eye. Thereconstructed image includes noise that is non-uniformly distributedacross the reconstructed image based on the position of the feature ofthe eye. The method of FIG. 9 may be implemented as applicable inconjunction with any of the hardware and systems described herein.

In some examples where the feature of the eye is the pupil, the noisemay be placed in a region in the region that is outside a perimeter ofthe pupil such that the noise is blocked from being received at theretina of the eye. In some examples where the feature of the eye is thefovea, the noise may be distributed in the reconstructed image such thata central foveal region is given preference in terms of optimization fornoise reduction, and outside of the foveal region noise is distributedin a graduated manner with more noise being distributed further awayfrom the foveal region.

In both examples, noise may be positioned in regions of the image thatare peripheral to tracked feature of the eye, where the perceptive powerof the eye is weaker. In accordance with the holographic display method,the reconstructed image may be perceived by the user as being of higherquality, since the noise is less perceptible by the user.

The methods and processes described herein may be tied to a computingsystem of one or more computing devices. In particular, such methods andprocesses may be implemented as an executable computer-applicationprogram, a network-accessible computing service, anapplication-programming interface (API), a library, or a combination ofthe above and/or other compute resources.

FIG. 10 schematically shows a simplified representation of a computingsystem 1000 configured to provide any to all of the computefunctionality described herein. Computing system 1000 may take the formof one or more personal computers, network-accessible server computers,tablet computers, home-entertainment computers, gaming devices, mobilecomputing devices, mobile communication devices (e.g., smart phone),virtual/augmented/mixed reality computing devices, wearable computingdevices, Internet of Things (IoT) devices, embedded computing devices,and/or other computing devices. For example, computing system 1000 maybe representative of near-eye display device 100 in FIG. 1 andholographic display system 200 in FIG. 2.

Computing system 1000 includes a logic subsystem 1002 and a storagesubsystem 1004. Computing system 1000 may optionally include a displaysubsystem 1006, input subsystem 1008, communication subsystem 1010,and/or other subsystems not shown in FIG. 10.

Logic subsystem 1002 includes one or more physical devices configured toexecute instructions. For example, the logic subsystem 1002 may beconfigured to execute instructions that are part of one or moreapplications, services, or other logical constructs. The logic subsystem1002 may include one or more hardware processors configured to executesoftware instructions. Additionally or alternatively, the logicsubsystem 1002 may include one or more hardware or firmware devicesconfigured to execute hardware or firmware instructions. Processors ofthe logic subsystem 1002 may be single-core or multi-core, and theinstructions executed thereon may be configured for sequential,parallel, and/or distributed processing. Individual components of thelogic subsystem 1002 optionally may be distributed among two or moreseparate devices, which may be remotely located and/or configured forcoordinated processing. Aspects of the logic subsystem 1002 may bevirtualized and executed by remotely-accessible, networked computingdevices configured in a cloud-computing configuration.

Storage subsystem 1004 includes one or more physical devices configuredto temporarily and/or permanently hold computer information such as dataand instructions executable by the logic subsystem 1002. When thestorage subsystem 1004 includes two or more devices, the devices may becollocated and/or remotely located. Storage subsystem 1004 may includevolatile, nonvolatile, dynamic, static, read/write, read-only,random-access, sequential-access, location-addressable,file-addressable, and/or content-addressable devices. Storage subsystem1004 may include removable and/or built-in devices. When the logicsubsystem 1002 executes instructions, the state of storage subsystem1004 may be transformed—e.g., to hold different data.

Aspects of logic subsystem 1002 and storage subsystem 1004 may beintegrated together into one or more hardware-logic components. Suchhardware-logic components may include program- and application-specificintegrated circuits (PASIC/ASICs), program- and application-specificstandard products (PSSP/ASSPs), system-on-a-chip (SOC), and complexprogrammable logic devices (CPLDs), for example.

The logic subsystem 1002 and the storage subsystem 1004 may cooperate toinstantiate one or more logic machines. As used herein, the term“machine” is used to collectively refer to the combination of hardware,firmware, software, instructions, and/or any other componentscooperating to provide computer functionality. In other words,“machines” are never abstract ideas and always have a tangible form. Amachine may be instantiated by a single computing device, or a machinemay include two or more sub-components instantiated by two or moredifferent computing devices. In some implementations a machine includesa local component (e.g., software application executed by a computerprocessor) cooperating with a remote component (e.g., cloud computingservice provided by a network of server computers). The software and/orother instructions that give a particular machine its functionality mayoptionally be saved as one or more unexecuted modules on one or moresuitable storage devices.

When included, display subsystem 1006 may be used to present a visualrepresentation of data held by storage subsystem 1004. This visualrepresentation may take the form of a graphical user interface (GUI).Display subsystem 1006 may include one or more display devices utilizingvirtually any type of technology. In some implementations, displaysubsystem may include one or more virtual-, augmented-, or mixed realitydisplays.

When included, input subsystem 1008 may comprise or interface with oneor more input devices. An input device may include a sensor device or auser input device. Examples of user input devices include a keyboard,mouse, touch screen, or game controller. In some embodiments, the inputsubsystem may comprise or interface with selected natural user input(NUI) componentry. Such componentry may be integrated or peripheral, andthe transduction and/or processing of input actions may be handled on-or off-board. Example NUI componentry may include a microphone forspeech and/or voice recognition; an infrared, color, stereoscopic,and/or depth camera for machine vision and/or gesture recognition; ahead tracker, eye tracker, accelerometer, and/or gyroscope for motiondetection and/or intent recognition.

When included, communication subsystem 1010 may be configured tocommunicatively couple computing system 1000 with one or more othercomputing devices. Communication subsystem 1010 may include wired and/orwireless communication devices compatible with one or more differentcommunication protocols. The communication subsystem 1010 may beconfigured for communication via personal-, local- and/or wide-areanetworks.

The methods and processes disclosed herein may be configured to giveusers and/or any other humans control over any private and/orpotentially sensitive data. Whenever data is stored, accessed, and/orprocessed, the data may be handled in accordance with privacy and/orsecurity standards. When user data is collected, users or otherstakeholders may designate how the data is to be used and/or stored.Whenever user data is collected for any purpose, the user owning thedata should be notified, and the user data should only be collected whenthe user provides affirmative consent. If data is to be collected, itcan and should be collected with the utmost respect for user privacy. Ifthe data is to be released for access by anyone other than the user orused for any decision-making process, the user's consent may becollected before using and/or releasing the data. Users may opt-inand/or opt-out of data collection at any time. After data has beencollected, users may issue a command to delete the data, and/or restrictaccess to the data. All potentially sensitive data optionally may beencrypted and/or, when feasible anonymized, to further protect userprivacy. Users may designate portions of data, metadata, orstatistics/results of processing data for release to other parties,e.g., for further processing. Data that is private and/or confidentialmay be kept completely private, e.g., only decrypted temporarily forprocessing, or only decrypted for processing on a user device andotherwise stored in encrypted form. Users may hold and controlencryption keys for the encrypted data. Alternately or additionally,users may designate a trusted third party to hold and control encryptionkeys for the encrypted data, e.g., so as to provide access to the datato the user according to a suitable authentication protocol.

In an example, a holographic display system comprises an eye trackerconfigured to determine a position of a feature of an eye, a lightsource configured to output image light, and a digital dynamic hologramconfigured to receive the image light from the light source andspatially modulate the image light based on a target image to form areconstructed image in the eye, wherein the reconstructed image includesnoise that is non-uniformly distributed across the reconstructed imagebased on the position of the feature of the eye. In this example and/orother examples, the reconstructed image may include a plurality ofregions dynamically determined based on the position of the feature ofthe eye, and different regions may have different noise thresholds suchthat regions closer to the position of the feature of the eye includeless noise and regions further from the position of the feature of theeye include more noise. In this example and/or other examples, theplurality of regions may be concentric regions centered on the positionof the feature of the eye. In this example and/or other examples, thefeature of the eye may be a fovea in a retina of the eye. In thisexample and/or other examples, the feature of the eye may be a pupil ofthe eye. In this example and/or other examples, a size of thereconstructed image may be larger than a maximum pupil diameter of theeye, and the noise may be positioned in the reconstructed image outsideof the pupil of the eye. In this example and/or other examples, thetarget image may include a plurality of image pixels, each image pixelmay have a target intensity, and the digital dynamic hologram may beconfigured, for each of a plurality of display pixels corresponding tothe plurality of image pixels, to modulate a phase of an incidentwavefront of the image light based on the target intensity of thecorresponding image pixel to output an actual intensity, wherein adifference between the target intensity and the actual intensity may bebased on a noise threshold that is determined based on the position ofthe pixel within the reconstructed image relative to the position of thefeature of the eye. In this example and/or other examples, the noise maybe distributed as a function of a distance relative to the feature ofthe eye. In this example and/or other examples, the actual intensity ofeach display pixel of the reconstructed image may be determined using aniterative hologram design algorithm. In this example and/or otherexamples, the holographic display may be a near-eye display of a headmounted device.

In an example, a holographic display method comprises determining, viaan eye tracker, a position of a feature of an eye, generating a targetimage, directing image light from a light source to a digital dynamichologram, and spatially modulating, via the digital dynamic hologram,the image light based on the target image to form a reconstructed imagein the eye, wherein the reconstructed image includes noise that isnon-uniformly distributed across the reconstructed image based on theposition of the feature of the eye. In this example and/or otherexamples, the reconstructed image may include a plurality of regionsdynamically determined based on the position of the feature of the eye,and different regions may have different noise thresholds such thatregions closer to the position of the feature of the eye include lessnoise and regions further from the position of the feature of the eyeinclude more noise. In this example and/or other examples, the pluralityof regions may be concentric regions centered on the position of thefeature of the eye. In this example and/or other examples, the noise maybe distributed as a function of a distance relative to the feature ofthe eye. In this example and/or other examples, the feature of the eyemay be a fovea in a retina of the eye. In this example and/or otherexamples, the feature of the eye may be a pupil of the eye. In thisexample and/or other examples, a size of the reconstructed image may belarger than a maximum pupil diameter of the eye, and the noise may bepositioned in the reconstructed image outside of the pupil of the eye.

In an example, a near-eye display device comprises a holographic displaysystem, comprising an eye tracker configured to determine a position ofa fovea in a retina of an eye of the wearer of the near-eye displaydevice, a light source configured to output image light, and a digitaldynamic hologram configured to receive the image light from the lightsource and spatially modulate the image light based on a target image toform a reconstructed image in the eye, wherein the reconstructed imageincludes noise that is non-uniformly distributed across thereconstructed image based on the position of the fovea. In this exampleand/or other examples, the reconstructed image may include a pluralityof regions dynamically determined based on the position of fovea, anddifferent regions may have different noise thresholds such that regionscloser to the position of the fovea include less noise and regionsfurther from the position of the fovea include more noise. In thisexample and/or other examples, the plurality of regions may beconcentric regions centered on the position of the fovea.

It will be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. As such, various acts illustrated and/ordescribed may be performed in the sequence illustrated and/or described,in other sequences, in parallel, or omitted. Likewise, the order of theabove-described processes may be changed.

The subject matter of the present disclosure includes all novel andnon-obvious combinations and sub-combinations of the various processes,systems and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

1. A holographic display system, comprising: an eye tracker configuredto determine a position of a feature of an eye; a light sourceconfigured to output image light; and a digital dynamic hologramconfigured to receive the image light from the light source andspatially modulate the image light based on a target image to form areconstructed image in the eye, wherein the reconstructed image includesnoise that is non-uniformly distributed across the reconstructed imagebased on the position of the feature of the eye.
 2. The holographicdisplay system of claim 1, wherein the reconstructed image includes aplurality of regions dynamically determined based on the position of thefeature of the eye, and wherein different regions have different noisethresholds such that regions closer to the position of the feature ofthe eye include less noise and regions further from the position of thefeature of the eye include more noise.
 3. The holographic display systemof claim 2, wherein the plurality of regions are concentric regionscentered on the position of the feature of the eye.
 4. The holographicdisplay system of claim 1, wherein the feature of the eye is a fovea ina retina of the eye.
 5. The holographic display system of claim 1,wherein the feature of the eye is a pupil of the eye.
 6. The holographicdisplay system of claim 5, wherein a size of the reconstructed image islarger than a maximum pupil diameter of the eye, and wherein the noiseis positioned in the reconstructed image outside of the pupil of theeye.
 7. The holographic display system of claim 1, wherein the targetimage includes a plurality of image pixels, each image pixel having atarget intensity, and wherein the digital dynamic hologram isconfigured, for each of a plurality of display pixels corresponding tothe plurality of image pixels, to modulate a phase of an incidentwavefront of the image light based on the target intensity of thecorresponding image pixel to output an actual intensity, wherein adifference between the target intensity and the actual intensity isbased on a noise threshold that is determined based on the position ofthe pixel within the reconstructed image relative to the position of thefeature of the eye.
 8. The holographic display system of claim 7,wherein the noise is distributed as a function of a distance relative tothe feature of the eye.
 9. The holographic display system of claim 7,wherein the actual intensity of each display pixel of the reconstructedimage is determined using an iterative hologram design algorithm. 10.The holographic display system of claim 1, wherein the holographicdisplay is a near-eye display of a head mounted device.
 11. Aholographic display method, comprising: determining, via an eye tracker,a position of a feature of an eye; generating a target image; directingimage light from a light source to a digital dynamic hologram; andspatially modulating, via the digital dynamic hologram, the image lightbased on the target image to form a reconstructed image in the eye,wherein the reconstructed image includes noise that is non-uniformlydistributed across the reconstructed image based on the position of thefeature of the eye.
 12. The method of claim 11, wherein thereconstructed image includes a plurality of regions dynamicallydetermined based on the position of the feature of the eye, and whereindifferent regions have different noise thresholds such that regionscloser to the position of the feature of the eye include less noise andregions further from the position of the feature of the eye include morenoise.
 13. The method of claim 12, wherein the plurality of regions areconcentric regions centered on the position of the feature of the eye.14. The method of claim 11, wherein the noise is distributed as afunction of a distance relative to the feature of the eye.
 15. Themethod of claim 11, wherein the feature of the eye is a fovea in aretina of the eye.
 16. The method of claim 11, wherein the feature ofthe eye is a pupil of the eye.
 17. The method of claim 16, wherein asize of the reconstructed image is larger than a maximum pupil diameterof the eye, and wherein the noise is positioned in the reconstructedimage outside of the pupil of the eye.
 18. A near-eye display devicecomprising: a holographic display system, comprising: an eye trackerconfigured to determine a position of a fovea in a retina of an eye ofthe wearer of the near-eye display device; a light source configured tooutput image light; and a digital dynamic hologram configured to receivethe image light from the light source and spatially modulate the imagelight based on a target image to form a reconstructed image in the eye,wherein the reconstructed image includes noise that is non-uniformlydistributed across the reconstructed image based on the position of thefovea.
 19. The near-eye display device of claim 18, wherein thereconstructed image includes a plurality of regions dynamicallydetermined based on the position of the fovea, and wherein differentregions have different noise thresholds such that regions closer to theposition of the fovea include less noise and regions further from theposition of the fovea include more noise.
 20. The near-eye displaydevice of claim 18, wherein the plurality of regions are concentricregions centered on the position of the fovea.